Over the past decade, the ever-decreasing power requirements of electronic devices has lead to considerable scientific interest in energy harvesting technologies. In particular, there has been significant interest in the area of vibration energy harvesting (VEH), particularly for single-degree-of-freedom (SDOF) piezoelectric and magnetic harvesters. Although there are a number of commercially available SDOF harvesters, there exist a number of continuing challenges that prevent widespread application of VEH, such as limited operational bandwidth and low power density. In many practical applications, the direction of the incident vibration may vary, so another challenge is the uni-axial nature of many harvesters, particularly cantilever-based piezoelectric designs and SDOF electromagnetic designs.
In addition, existing SDOF vibration energy harvesters generally are relatively heavy and/or too large for some applications, particularly those in aerospace fields. Existing SDOF harvesting devices can generally only take advantage of vibration of the host structure along a single axis. For host structures such as aircraft, it may frequently be the case that the vibration energy associated with vibration of the host structure occurs across multiple axes.
It is desired to address or ameliorate one or more shortcomings or disadvantages associated with existing vibration energy conversion devices, or to at least provide a useful alternative thereto.